Search Results

A 3-dimensional numerical study has been conducted investigating the combustion process in a VW 1.9l TDI Diesel engine. Simulations were performed modeling the spray injection of a 5-hole Diesel injector in a pressure chamber. A graphical methodology was utilized to match the spray resulting from the widely used Discrete Droplet Spray model to pressure chamber spray images. Satisfactory agreement has been obtained regarding the simulated and experimental spray penetration and cone angles. Thereafter, the combustion process in the engine was simulated. Using engine measurements to initialize the combustion chamber conditions, the compression stroke, the spray injection and the combustion simulation was performed. The novel RTZF two-zone flamelet combustion model was used for the combustion simulation and was tested for partial load operating conditions. An objective analysis of the model is presented including the results of a numerical parameter study.

An overview is given on the state of the art of a new catalytic exhaust gas aftertreatment device for diesel engines. The function of a precious metal based, flow-through type diesel oxidation catalyst is explained. Much attention is paid to the durability of the diesel oxidation catalyst and especially to the influence of poisoning elements on the catalytic activity. Detailed data on the interaction of poisoning elements such as sulfur, zinc and phosphorus with the catalytic active sites are given. Finally it is demonstrated that it is possible to meet the stringent emission standards for diesel passenger cars in Europe with a new catalyst generation over 80.000 km AMA aging.

The vehicle fleet differs in mass, geometry, stiffness and many other parameters. These differences are consequences of different design objectives for these vehicles and result from consumer demand, environmental and safety considerations etc. Accident research shows that the injury outcome differs in some cases, when two vehicles collide. Scientists often discuss a list of features that are assumed to be relevant for compatibility of vehicles. The relevance of these potentially important compatibility features and expected compatibility measures is examined from the perspective of accident analysis. An overview of this accident research is given and crash tests and measures are discussed that correspond with these findings.

The turbulent flow around vehicles causes high amplitude pressure fluctuations at the underbody, consisting of both hydromechanic and acoustic contributions. This induces vibrations in the underbody structures, which in turn may lead to sound transmission into the passenger compartment, especially at low frequencies. To study these phenomena we present a run time fully coupled acoustic-fluid-structure interaction framework expanding a validated hybrid CFD-CAA solver. The excited and vibrating underbody is resembled by an aluminium plate in the underbody of the SAE body which allows for sound transmission into the interior. Different excitation situations are generated by placing obstacles at the underbody upstream of the aluminium plate. For this setup we carry out a fully coupled simulation of flow, acoustics and vibration of the plate.

In the new century the automotive industry is transforming itself from an entirely mechanical industry to an industry that is driven by electronics and services. The companies who will be most successful are those who are able to control, drive and renew the architectural concepts enabling the introduction of state-of-the-art information technology to the car and its supporting infrastructure. This paper will first define the term architecture and will elaborate about the increasing relevance of architectural thinking in the automotive domain. Architectural leadership will be defined to mean control (proprietary ownership of components and/or interfaces), creation of a de-facto or legal standard as well as renewal (creation of new products and markets utilizing new linkages of existing architectures). In the second part examples of successful and less successful approaches for establishing architectural leadership in the automotive industry are discussed.

Crank-angle resolved, gas temperatures are determined in the combustion chamber of a Volkswagen (VW) standard-production, port-injected SI engine. During idle, two different methods are applied: (1) a direct spectroscopic emission-absorption technique at a resonance line of potassium, seeded to the air stream to generate sufficient spectral absorptance (‘colouring’ technique), and (2) a more standard, indirect method in which temperatures are derived from pressure recordings using a two-zone thermodynamic model. Combustion temperatures obtained during idle with both the spectroscopic (1) and ‘two-zone’ (2) methods are in good agreement. In addition, the spectroscopic technique is extended to transient operating conditions where the ‘two-zone’ method is not applicable. Combustion temperatures measured during cold-start and abrupt load alteration are in good agreement with former investigations.

The regulations for mobile applications will become stricter in Euro 6 and further emission levels and require the use of active aftertreatment methods for NOX and particulate matter. SCR and LNT have been both used commercially for mobile NOX removal. An alternative system is based on the combination of these two technologies. Developments of catalysts and whole systems as well as final vehicle demonstrations are discussed in this study. The small and full-size catalyst development experiments resulted in PtRh/LNT with optimized noble metal loadings and Cu-SCR catalyst having a high durability and ammonia adsorption capacity. For this study, an aftertreatment system consisting of LNT plus exhaust bypass, passive SCR and engine independent reductant supply by on-board exhaust fuel reforming was developed and investigated. The concept definition considers NOX conversion, CO2 drawback and system complexity.

Due to the increase in demand for comfort and safety features in today's automobiles, the internal vehicle communication networks necessary to accommodate these features are very complex. These networks represent a heterogeneous architecture consisting of several ECUs exchanging information via bus systems such as CAN, LIN, MOST, or FlexRay buses. Development and verification of internal vehicle networks include multiple design layers. These layers are the logical layer represented by the software application, the associated data link layer, and the physical connection layer containing bus interfaces, wires, and termination. Verification of these systems in the early stages of the design process (before a physical network is available for testing) has become a critical need. As a result, the need to simulate these designs at all their levels of complexity has become critically important.

This paper summarizes the development of a wireless message from infrastructure-to-vehicle (I2V) for safety applications based on Dedicated Short-Range Communications (DSRC) under a cooperative agreement between the Crash Avoidance Metrics Partners LLC (CAMP) and the Federal Highway Administration (FHWA). During the development of the Curve Speed Warning (CSW) and Reduced Speed Zone Warning with Lane Closure (RSZW/LC) safety applications [1], the Basic Information Message (BIM) was developed to wirelessly transmit infrastructure-centric information. The Traveler Information Message (TIM) structure, as described in the SAE J2735, provides a mechanism for the infrastructure to issue and display in-vehicle signage of various types of advisory and road sign information. This approach, though effective in communicating traffic advisories, is limited by the type of information that can be broadcast from infrastructures.

Within the European research programme IDEA (Integrated Diesel European Action), detailed experimental and theoretical studies of the fundamental phenomena of the Diesel engine like flow, injection, mixture formation, auto-ignition, combustion and pollutant formation were carried out to improve knowledge and to set up models for a simulation code. Because this basic research of the Diesel combustion process is very complex and cost intensive, it was carried out jointly by the JRC (Joint Research Committee), an association of European car manufacturers (Fiat, Peugeot SA, Renault, Volvo and Volkswagen). The activities were also subsidized by the Commission of the European Communities and the Swedish National Board of Technical Development. The results of the research work will support the design of even more efficient engines and the further reduction of soot and NOx emissions and will also enable the companies to reduce time and cost in developing new engines.

For the measurement of NO and NO2 the CLD-analyzer (chemiluminescense detector) has been used for more than twenty-five years. The disadvantage of the CLD is that NO can be measured only. To obtain total NOX (NO+NO2) the exhaust gas sample has to flow through a catalytic converter, which reduces NO2 to NO. The converter has a efficiency between 90 and 100%. For precise NO and NO2 values it is an advantage to analyze NO and NO2 directly. This paper describes a new UV NOX-analyzer for the simultaneous measurement of NO and NO2. Two different configurations, for high and low concentrations, eg. CVS-bag analysis are presented. The performance of the analyzers is documented in comparison to the UV-RAS analyzer with converter for NOX [1] and the conventional CLD-analyzer. The benefits of the new analyzer compared to analyzers equipped with a converter are given in detailed test results.

For substantial reduction of fuel consumption of their vehicle fleet, Volkswagen AG has decided to develop spark-ignition engines with direct fuel injection. To launch this new engine concept with stratified lean operation mode while at the same time meeting the stringent EU IV emission standards, it was necessary to develop a suitable exhaust gas aftertreatment system. This was achieved as part of an intensive co-operation between Volkswagen AG and OMG, formerly dmc2 Degussa Metals Catalysts Cerdec AG. The paper describes the demands for exhaust gas aftertreatment due to lean burn operation. In addition the main development steps of the exhaust gas aftertreatment system for Volkswagen FSI engines and catalyst durability over vehicle lifetime are discussed. Focus is laid on the catalyst system design and coating variations. Volkswagen developed a new closed-loop emission control management system which uses NOx-sensor signals for the first time worldwide.

A uniform flow distribution at converter inlet is one of the fundamental requirements to meet high catalytic efficiency. Commonly used tools for optimization of the inlet flow distribution are flow measurements as well as CFD analysis. This paper puts emphasis on the experimental procedures and results. The interaction of flow measurements and CFD is outlined. The exhaust gas flow is transient, compressible and hot, making in-situ flow measurements very complex. On the other hand, to utilize the advantages of flow testing at steady-state and cold conditions the significance of these results has to be verified first. CFD analysis under different boundary conditions prove that - in a first approach - the flow situation can be regarded as a sequence of successive, steady-state situations. Using the Reynolds analogy a formula for the steady-state, cold test mass flow is derived, taking into account the cylinder displacement and the rated speed.

The current trend in automobiles is towards electrical vehicles, but for the most part these vehicles still require an internal combustion engine to provide additional range and flexibility. These engines are under stringent emissions regulations, in particular, for the reduction of CO2. Gas engines which run lean burn combustion systems provide a viable route to these emission reductions, however designing these engines to provide sustainable and controlled combustion under lean conditions at λ=2.0 is challenging. To address this challenge, it is possible to use a scavenged Pre-Chamber Ignition (PCI) system which can deliver favorable conditions for ignition close to the spark plug. The lean charge in the main combustion chamber is then ignited by flame jets emanating from the pre-chamber nozzles. Accurate prediction of flame kernel development and propagation is essential for the analysis of PCI systems.

Compatibility has been a research issue for many years now. It has gained more importance recently due to significant improvements in primary and secondary safety. Using a rigorous approach, combining accident research and theoretical scientific considerations, measures to improve vehicle-vehicle compatibility, with an emphasis on feasibility, were discussed. German accident research statistics showed that frontal impacts are of higher statistical significance than side impacts. Based on this and the high potential for improvement due high available deformation energy, the frontal impact configuration was identified as the most appropriate collision mode for addressing the compatibility issue. In side impacts, accident avoidance was identified as the most feasible and sensible measure. For frontal vehicle-vehicle impacts, both trucks and passenger cars were identified as opponents of high statistical significance.

The accelerated processes in vehicle development require new technologies for function development and validation. With this motivation, Function-in-the-Loop (FiL) simulation was developed as a link between Software-in-the-Loop (SiL) and Hardware-in-the-Loop (HiL) simulation. The combination of real Electronic Control Unit (ECU) hardware and software in conjunction with virtual components is very well suited for function development and testing. This approach opens up new possibilities for mechatronic systems that would otherwise require special test benches. For this reason, an Electric Power Steering (EPS) was transferred to a virtual environment using FiL simulation. This enables a wide range of applications, from EPS testing to the development of connected driving functions on an integrated platform. Right from the early development phases, the technology can be used purposefully with short integration cycles.

Mixture formation analysis in the combustion chamber of a slightly modified mass-production SI engine with port-fuel injection using nonintrusive laser measurement techniques is presented. Laser Raman scattering and planar laser-induced tracer fluorescence are employed to measure air-fuel ratio and residual gas content of the charge with and without spatial resolution. Single-cycle measurements as well as cycle-averaged measurements are performed. Engine operation parameters like load, speed, injection timing, spark timing, coolant temperature, and mean air-fuel ratio are changed to study whether the effects on mixture formation and engine performance can be resolved by the applied laser spectroscopic techniques. Mixture formation is also analyzed by measurement of the charge composition as a function of crank angle. Clear correlations of the charge composition data and engine operating conditions are seen.

Even though a number of developed countries enjoy a high level of vehicle safety, more than 1.2 million fatalities still occur each year on roadways worldwide. There remains a need to continue improving vehicle and road safety. New technologies in sensors and electronic control units, and the growing knowledge of car-to-car and car-to-infrastructure technologies have led to a fusion of the previously separated areas of accident avoidance (popularly known as active safety) and mitigation of injuries (popularly known as passive safety) into the newer concept of integrated vehicle safety. This new approach represents a further step toward lowering accident rates. This book, written by two of the foremost automotive engineering safety experts, takes a unique and comprehensive approach to describing all areas of vehicle safety: accident avoidance, pre-crash, mitigation of injuries, and post-crash technologies, providing a solutions-based perspective of integrated vehicle safety.

The paper describes detailed studies about the spray formation of a direct-injection high-pressure gasoline injector and the interaction of the droplets with the surrounding compressed air in pressure chamber experiments and inside an optically accessible research engine. Different optical techniques, like stroboscopic video technique, high-speed filming with flood-light illumination or with light-sheet illumination by a copper vapour laser, particle image velocimetry of the droplets, laser-induced fluorescence of the liquid phase, and spontaneous Raman spectroscopy for the measurement of the fuel/air ratio are used. From the recorded images spray characteristics such as spray penetration and spray cone angle are evaluated for different settings of the chamber pressure and temperature and for different rail pressures. The results show that all techniques are suitable to derive the quantities mentioned above.